Note 15 - Fair Value Measurements - Financial Assets and Liabilities Measured on a Non-recurring Basis (Details) - USD ($)		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Assets, fair value disclosure		$ 1,275,998,000	$ 1,340,767,000
Total Losses		(289,000)	874,000	$ 1,307,000
Fair Value, Measurements, Nonrecurring [Member]
Assets, fair value disclosure		53,297,000	73,493,000
Fair Value, Inputs, Level 1 [Member]
Assets, fair value disclosure		149,849,000	277,622,000
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Nonrecurring [Member]
Assets, fair value disclosure
Fair Value, Inputs, Level 2 [Member]
Assets, fair value disclosure		1,125,965,000	1,063,054,000
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Nonrecurring [Member]
Assets, fair value disclosure		9,023,000	5,677,000
Fair Value, Inputs, Level 3 [Member]
Assets, fair value disclosure		184,000	91,000
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Nonrecurring [Member]
Assets, fair value disclosure		44,274,000	67,816,000
Impaired Loans [Member]
Total Losses			25,000	322,000
Impaired Loans [Member] | Fair Value, Measurements, Nonrecurring [Member]
Assets, fair value disclosure		37,769,000	60,911,000
Impaired Loans [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Nonrecurring [Member]
Assets, fair value disclosure
Impaired Loans [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Nonrecurring [Member]
Assets, fair value disclosure
Impaired Loans [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Nonrecurring [Member]
Assets, fair value disclosure		37,769,000	60,911,000
Impaired Loans [Member] | Commercial Portfolio Segment [Member]
Total Losses			25,000	322,000
Impaired Loans [Member] | Commercial Portfolio Segment [Member] | Fair Value, Measurements, Nonrecurring [Member]
Assets, fair value disclosure		4,733,000	18,097,000
Impaired Loans [Member] | Commercial Portfolio Segment [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Nonrecurring [Member]
Assets, fair value disclosure
Impaired Loans [Member] | Commercial Portfolio Segment [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Nonrecurring [Member]
Assets, fair value disclosure
Impaired Loans [Member] | Commercial Portfolio Segment [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Nonrecurring [Member]
Assets, fair value disclosure		4,733,000	18,097,000
Impaired Loans [Member] | Commercial Real Estate Portfolio Segment [Member]
Total Losses
Impaired Loans [Member] | Commercial Real Estate Portfolio Segment [Member] | Fair Value, Measurements, Nonrecurring [Member]
Assets, fair value disclosure		26,186,000	31,459,000
Impaired Loans [Member] | Commercial Real Estate Portfolio Segment [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Nonrecurring [Member]
Assets, fair value disclosure
Impaired Loans [Member] | Commercial Real Estate Portfolio Segment [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Nonrecurring [Member]
Assets, fair value disclosure
Impaired Loans [Member] | Commercial Real Estate Portfolio Segment [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Nonrecurring [Member]
Assets, fair value disclosure		26,186,000	31,459,000
Impaired Loans [Member] | Residential Mortgage and Equity Lines Portfolio Segment [Member]
Assets, fair value disclosure		6,850,000	11,355,000
Total Losses
Impaired Loans [Member] | Residential Mortgage and Equity Lines Portfolio Segment [Member] | Fair Value, Inputs, Level 1 [Member]
Assets, fair value disclosure
Impaired Loans [Member] | Residential Mortgage and Equity Lines Portfolio Segment [Member] | Fair Value, Inputs, Level 2 [Member]
Assets, fair value disclosure
Impaired Loans [Member] | Residential Mortgage and Equity Lines Portfolio Segment [Member] | Fair Value, Inputs, Level 3 [Member]
Assets, fair value disclosure		6,850,000	11,355,000
Other Real Estate Owned [Member]
Total Losses	[1]	(619,000)	457,000	9,000
Other Real Estate Owned [Member] | Fair Value, Measurements, Nonrecurring [Member]
Assets, fair value disclosure	[1]	13,366,000	9,999,000
Other Real Estate Owned [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Nonrecurring [Member]
Assets, fair value disclosure	[1]
Other Real Estate Owned [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Nonrecurring [Member]
Assets, fair value disclosure	[1]	9,023,000	5,677,000
Other Real Estate Owned [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Nonrecurring [Member]
Assets, fair value disclosure	[1]	4,343,000	4,322,000
Investments in Venture Capital [Member]
Total Losses		330,000	392,000	$ 976,000
Investments in Venture Capital [Member] | Fair Value, Measurements, Nonrecurring [Member]
Assets, fair value disclosure		2,162,000	2,583,000
Investments in Venture Capital [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Nonrecurring [Member]
Assets, fair value disclosure
Investments in Venture Capital [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Nonrecurring [Member]
Assets, fair value disclosure
Investments in Venture Capital [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Nonrecurring [Member]
Assets, fair value disclosure		$ 2,162,000	$ 2,583,000

[1] Other real estate owned balance of $12.7 million in the Consolidated Balance Sheets is net of estimated disposal costs.